In Act One, Ellen helps Richard prepare for a camping trip. Ellen: Oh, don't forget the mustard. And, oh, does anybody want ketchup? Richard: I might as well take it along. Ellen has offered to baby-sit for Max while Richard and Marilyn are away. Richard: Mom, we really appreciate your taking care of Max for the weekend and giving up your free time. Ellen: I love doing it. But Marilyn doesn't feel comfortable about leaving the baby. Marilyn: I'm really concerned about going away for the weekend, Ellen, and leaving you with the full responsibility of taking care of Max. Why is Marilyn so concerned about leaving Max?